Parabolic density function in sedimentary basin modelling

Rao, C. Visweswara; Chakravarthi, V.; Raju, M. L.

doi:10.1007/bf00876967

Cited by 25 publications

(11 citation statements)

References 6 publications

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“…Example plots of log(power spectrum)/wave number (rad/km) of some blocks (B1, B14, B18 and B23) used in the study. defined as (Rao et al 1993(Rao et al , 1994Chakravarthi et al 2001) Δρ…”

Section: Forward Modellingmentioning

confidence: 99%

“…Gravity method plays a vital role in recognition of sedimentary basins (Rao et al 1994;Ali et al 2014). There are varieties of techniques and methods for the interpretation of gravity anomalies over or due to sedimentary basins (e.g., Rao et al 1993Rao et al , 1994Chakravarthi 1995;Chakravarthi and Sundararajan 2005). The structure of the sedimentary basins is often derived from the gravity anomalies with constant density contrast throughout the section of the basins (Bott 1960).…”

Section: Introductionmentioning

confidence: 99%

“…The structure of the sedimentary basins is often derived from the gravity anomalies with constant density contrast throughout the section of the basins (Bott 1960). However, the density contrast of sedimentary rocks is not practically constant (Rao et al 1993(Rao et al , 1994Chakravarthi 1995;Chakravarthi and Sundararajan 2005).…”

Section: Introductionmentioning

confidence: 99%

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Mapping magnetic lineaments and subsurface basement beneath parts of Lower Benue Trough (LBT), Nigeria: Insights from integrating gravity, magnetic and geologic data

2018

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“…Example plots of log(power spectrum)/wave number (rad/km) of some blocks (B1, B14, B18 and B23) used in the study. defined as (Rao et al 1993(Rao et al , 1994Chakravarthi et al 2001) Δρ…”

Section: Forward Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mapping magnetic lineaments and subsurface basement beneath parts of Lower Benue Trough (LBT), Nigeria: Insights from integrating gravity, magnetic and geologic data

2018

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“…Granser 1987) or polynomial laws (e.g. Hermes 1986; Rao et al 1993; Garcia‐Abdeslem 2005; Chakravarthi & Sundararajan 2006). At shallow levels the sedimental overburden has a density of about 1900 kg m −3 .…”

Section: Database and Processingmentioning

confidence: 99%

Combining geophysical data sets to study the dynamics of shallow evaporites in urban environments: application to Hamburg, Germany

Dahm

Kühn

Ohrnberger

et al. 2010

Geophysical Journal International

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S U M M A R YShallowly situated evaporites in built-up areas are of relevance for urban and cultural development and hydrological regulation. The hazard of sinkholes, subrosion depressions and gypsum karst is often difficult to evaluate and may quickly change with anthropogenic influence. The geophysical exploration of evaporites in metropolitan areas is often not feasible with active industrial techniques.We collect and combine different passive geophysical data as microgravity, ambient vibrations, deformation and hydrological information to study the roof morphology of shallow evaporites beneath Hamburg, Northern Germany. The application of a novel gravity inversion technique leads to a 3-D depth model of the salt diapir under study. We compare the gravity-based depth model to pseudo-depths from H/V measurements and depth estimates from small-scale seismological array data. While the general range and trend of the diapir roof is consistent, a few anomalous regions are identified where H/V pseudo-depths indicate shallower structures not observed in gravity or array data. These are interpreted by shallow residual caprock floaters and zones of increased porosity.The shallow salt structure clearly correlates with a relative subsidence in the order of 2 mm yr −1 . The combined interpretation of roof morphology, yearly subsidence rates, chemical analyses of groundwater and of hydraulic head in aquifers indicates that the salt diapir beneath Hamburg is subject to significant ongoing dissolution that may possibly affect subrosion depressions, sinkhole distribution and land usage.The combined analysis of passive geophysical data may be exemplary for the study of shallow evaporites beneath other urban areas.

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“…Maxant, 1980;Rao, 1986;Rao et al, 1993Rao et al, , 1994. Furthermore, depth-variable densities have been used in forward and inverse gravity modelling, mostly applied to sedimentary basins (Cordell, 1973;Rao, 1986;Cowie & Karner, 1990;Rao et al, 1993Rao et al, , 1994Zhang et al, 2001;Welford et al, 2010). These forward gravity models have been developed for two or three dimensional bodies in Cartesian coordinates, which limits the applications to local scales.…”

Section: Introductionmentioning

confidence: 99%

Gravitational field calculation in spherical coordinates using variable densities in depth

Soler

Pesce

Giménez

et al. 2019

Geophysical Journal International

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SUMMARY We present a new methodology to compute the gravitational fields generated by tesseroids (spherical prisms) whose density varies with depth according to an arbitrary continuous function. It approximates the gravitational fields through the Gauss–Legendre Quadrature along with two discretization algorithms that automatically control its accuracy by adaptively dividing the tesseroid into smaller ones. The first one is a preexisting 2-D adaptive discretization algorithm that reduces the errors due to the distance between the tesseroid and the computation point. The second is a new density-based discretization algorithm that decreases the errors introduced by the variation of the density function with depth. The amount of divisions made by each algorithm is indirectly controlled by two parameters: the distance-size ratio and the delta ratio. We have obtained analytical solutions for a spherical shell with radially variable density and compared them to the results of the numerical model for linear, exponential, and sinusoidal density functions. The heavily oscillating density functions are intended only to test the algorithm to its limits and not to emulate a real world case. These comparisons allowed us to obtain optimal values for the distance-size and delta ratios that yield an accuracy of 0.1 per cent of the analytical solutions. The resulting optimal values of distance-size ratio for the gravitational potential and its gradient are 1 and 2.5, respectively. The density-based discretization algorithm produces no discretizations in the linear density case, but a delta ratio of 0.1 is needed for the exponential and most sinusoidal density functions. These values can be extrapolated to cover most common use cases, which are simpler than oscillating density profiles. However, the distance-size and delta ratios can be configured by the user to increase the accuracy of the results at the expense of computational speed. Finally, we apply this new methodology to model the Neuquén Basin, a foreland basin in Argentina with a maximum depth of over 5000 m, using an exponential density function.

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Parabolic density function in sedimentary basin modelling

Cited by 25 publications

References 6 publications

Mapping magnetic lineaments and subsurface basement beneath parts of Lower Benue Trough (LBT), Nigeria: Insights from integrating gravity, magnetic and geologic data

Mapping magnetic lineaments and subsurface basement beneath parts of Lower Benue Trough (LBT), Nigeria: Insights from integrating gravity, magnetic and geologic data

Combining geophysical data sets to study the dynamics of shallow evaporites in urban environments: application to Hamburg, Germany

Gravitational field calculation in spherical coordinates using variable densities in depth

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